In recent decades, a centrifugal pump, especially an electric pump, has been widely used in a heat circulation system. Currently, the heat circulation system is developed towards high performance and compactification. Accordingly, a mounting space for the electric pump is limited, and further, the pump is required to have a small overall dimension and a small volume. The impeller employed in the pump correspondingly has a small diameter so as to ensure the pump to have a small overall dimension and a small volume. In this case, an impeller of a conventional pump can hardly meet the high lift requirement when the pump employs the impeller during a low flow-rate situation.
Therefore, it is necessary to improve the conventional technology so as to address the above technical issues.